1. Technical Field
The present invention relates to an X-ray tube.
2. Description of the Related Art
An X-ray tube is based on the principle of generating X-rays using a cathode made from a filament and an anode made from a metallic material. When a high voltage is applied between the cathode and the anode, thermal electrons generated in the cathode are made to collide with the anode to generate X-rays.
The inside of the X-ray tube may be kept in a vacuum state, in order to avoid reductions in kinetic energy and deflections, which may otherwise occur as electrons collide with air molecules while traveling towards the target. The target can be made of a thin layer of metal, the thickness of which can be determined in consideration of the penetration depth of the electrons and heat-absorbing capacity.
The X-ray tube can be divided into a fixed type and a rotating type, according to the operation of the anode. A rotating X-ray tube can be substantially the same as the fixed X-ray tube, except that the anode may rotate to better disperse the heat generated in the target.
A conventional X-ray tube, such as that illustrated in FIG. 1, may experience an anode heel effect, in which the intensity of the X-rays is higher in the direction of the cathode from the midpoint, so that the effective focal spot size is larger, while the intensity of the X-rays is lower in the direction of the anode, so that the effective focal spot size is smaller.
Thus, in practice, a technician may move towards the parts closer to the cathode when acquiring an image for a thick portion and move towards the parts closer to the anode when acquiring an image for a thin portion, when operating an X-ray machine. This uneven distribution of X-ray intensity is caused by the inclination of the anode.